Part 19 (1/2)

This is a concrete acid, extracted from a salt procured froh borax has been very long ee of its origin, and of the methods by which it is extracted and purified; there is reason to believe it to be a native salt, found in the earth in certain parts of the east, and in the water of some lakes The whole trade of borax is in the hands of the Dutch, who have been exclusively possessed of the art of purifying it till very lately, that Messrs L'Eguillier of Paris have rivalled them in the manufacture; but the process still remains a secret to the world

By chemical analysis we learn that borax is a neutral salt with excess of base, consisting of soda, partly saturated with a peculiar acid long called _Ho's sedative salt_, now _the boracic acid_ This acid is found in an uncombined state in the waters of certain lakes That of Cherchiais in Italy contains 94-1/2 grains in each pint of water

To obtain boracic acid, dissolve so water, filtrate the solution, and add sulphuric acid, or any other having greater affinity to soda than the boracic acid; this latter acid is separated, and is procured in a crystalline for for the process by which it is obtained, and was consequently supposed to differ according to the nature of the acid e it froed that it is identically the same acid, in whatever way procured, provided it be properly purified fro, and by repeated solution and cristallization It is soluble both in water and alkohol, and has the property of coreen colour to the flame of that spirit This circu copper, which is not confirmed by any decisive experiment On the contrary, if it contain any of that metal, it must only be considered as an accidental mixture It coh, in thisany of the metals directly, this combination is readily affected by compound affinity

The Table presents its combinations in the order of affinity in the hue in the order e operate via sicca; for, in that case, argill, though the last in our list, must be placed immediately after soda

The boracic radical is hitherto unknown; no experi as yet been able to decoy with the other acids, that oxygen exists in its co principle

TABLE _of the Combinations of arseniac Acid, with the Salifiable Bases, in the Order of Affinity_

_Bases_ _Neutral Salts_

Linesia nesia

Potash potash

Soda soda

Aanese anese

iron iron

lead lead

tin tin

cobalt cobalt

copper copper

nickel nickel

bismuth bismuth

mercury old gold

platina platina

Argill argill

_Note_--This order of salts was entirely unknown to the antient chemists Mr Macquer, in 1746, discovered the combinations of arseniac acid with potash and soda, to which he gave the name of _arsenical neutral salts_--A

SECT XXIII--_Observations upon arseniac Acid, and its Combinations_

In the Collections of the Academy for 1746, Mr Macquer shows that, when a mixture of white oxyd of arsenic and nitre are subjected to the action of a strong fire, a neutral salt is obtained, which he calls _neutral salt of arsenic_ At that tiular phenomenon, in which a metal acts the part of an acid, was quite unknown; butthis process, the arsenic becoen of the nitric acid; it is thus converted into a real acid, and combines with the potash There are otherits acid free from combination The most simple and most effectual of these is as follows: Dissolve white oxyd of arsenic in three parts, by weight, ofstate, add two parts of nitric acid, and evaporate to dryness In this process the nitric acid is decoen unites with the oxyd of arsenic, and converts it into an acid, and the nitrous radical flies off in the state of nitrous gas; whilst the as, and may be collected in proper vessels The arseniac acid is entirely freed fro it in a crucible till it begins to grow red; what remains is pure concrete arseniac acid

Mr Scheele's process, which was repeated with great success by Mr Morveau, in the laboratory at Dijon, is as follows: Distil anese, this converts it into oxygenated anese, receive this in a recipient containing white oxyd of arsenic, covered by a little distilled water; the arsenic deco off its supersaturation of oxygen, the arsenic is converted into arseniac acid, and the oxygenated ht back to the state of common muriatic acid The two acids are separated by distillation, with a gentle heat increased towards the end of the operation, the muriatic acid passes over, and the arseniac acid remains behind in a white concrete form

The arseniac acid is considerably less volatile than white oxyd of arsenic; it often contains white oxyd of arsenic in solution, owing to its not being sufficiently oxygenated; this is prevented by continuing to add nitrous acid, as in the foras is produced Fro definition of arseniac acid It is a white concrete metallic acid, foren, fixed in a red heat, soluble in water, and capable of co with many of the salifiable bases